General Sumbeiywo was fiercely loyal to then-President Daniel arap Moi. During a 1982 coup attempt, he'd raced to Mr. Moi's home to protect him. Off and on since 1987, he had sometimes been involved with the Sudan negotiations. But the president's order caught him off guard.

The general was dumbstruck. This was Africa's longest civil war - a seemingly intractable 18-year conflict between Muslim Arab northerners and mostly Christian black southerners. Some 2 million people had died. Four million had been forced to flee their homes. And at least five major peacemaking efforts over 13 years had failed. Yet if peace could be found in oil-rich and populous Sudan, it could usher in a new era of trade and prosperity in neighboring Kenya and across northeast Africa.

After stammering something, Sumbeiywo hung up. Then, he phoned back to try to reject the assignment. But Moi wouldn't take the call. So, Sumbeiywo did the only thing he could think of: He started a three-day fast "to get very close to God."

It was not the last time he would seek divine help. Over the next 3-1/2 grueling years of peace talks, he would muster the persistence of the biblical Joseph, the wisdom of an African chief, and the ingenuity of a modern mediator. And eventually the process he led would become what many now see as a gold standard for making peace in Africa.

"General Sumbeiywo should win the Nobel Peace Prize," says former Sen. John Danforth, who was President Bush's special envoy to Sudan from 2001 to 2004. "His ability to stay there in the talks and be an honest broker - and to listen to all the back and forth over such a long period of time - was essential, and was very largely responsible for the result," says Senator Danforth by phone from St. Louis.

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As a boy, Sumbeiywo would walk past one of the biggest trees in his rural village and see his father, the chief, sitting under its sprawling branches, surrounded by neighbors. His dad would listen for hours as people aired disagreements over such things as who owned a particular cow. Then he'd dispense his wisdom. Like many African chiefs, he'd stay under the tree until every villager had spoken.

Decades later, standing at the front of a conference room at a Kenyan resort hotel, Sumbeiywo drew upon his father's ways: He let the two sides vent.

The tall oak of a man with broad shoulders and a deep, soothing voice started his "ventilation sessions" in June of 2002 with a basic question for representatives from the Khartoum government in the north and the Sudan People's Liberation Movement (SPLA) in the south: "Why are you at war?"

For two weeks, they "steamed out" as Sumbeiywo filled page after page of flip-chart pads. He'd scrawl things like "oil" and "sharia" and "religion" and "self-determination" on the pages, and then tape them up around the room.

The words were shorthand for the root causes of conflict in Africa's largest country - a place more than three times the size of Texas that straddles the continent's great north-south divide between Arab and non-Arab, Muslim and Christian. Among the issues: How to split up Sudan's oil wealth; whether Islamic law (sharia) should be imposed on the south, where most people are Christian or animist; and how to assuage southern feelings of political and economic exclusion from power. (Similar feelings of marginalization also sparked the separate 2003 rebellion in Sudan's western Darfur region, which led to US charges of genocide against the Khartoum government.)

Often, things would get personal. Southern delegates said things like, "My name is Michael Deng, but I was made to change my name to Ahmed - and my mother was sold into slavery," remembers Susan Page, an American lawyer on Sumbeiywo's team.

The sessions helped Sumbeiywo see that, beyond anything else, the conflict was about one simple issue: "who is in control." War, he says, is about "power."

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The stream of vitriol exchanged might have made lesser mediators give up.

In July 2003, Sudan's military leader, President Omar al-Bashir, had just read Sumbeiywo's latest draft peace proposal, and his raging response came in a public speech: Sumbeiywo could take that draft and "soak it, and drink it, and go to hell."

At the same time, the atmosphere between the two negotiating teams at a Kenyan hotel wasn't any better. "It was a horrible session," recalls Ms. Page.

At moments like that, Sumbeiywo confesses today, he wrestled with how much he'd rather be enjoying the serenity of the dairy farm he owns in Kenya's countryside. Or of how much he'd rather be with his wife and children. Already he had missed so many birthdays and holidays.

But he felt a duty to press on. So he'd go to his hotel room, sink to his knees and, as he puts it, "seek God's face."

On those dark nights, he'd begin to find solace in things like the biblical story of Joseph, who spent years in servitude and prison before achieving great things. "Even when he was in prison and forgotten," Sumbeiywo says, "he still didn't give up."

On his knees, Sumbeiywo would ask God for direction. After drifting off to sleep, he'd awake with a start - and a "vision" or "insight," as Page describes it - about how to proceed. In those early morning hours, he'd write out solutions to the impasse of the previous day. "So many parts" of what became the final agreement," he says, "were written during those nights."

And many times that inspiration gave him the stamina to press on, despite the vitriol spewed at him.

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The two sides were achingly close to a breakthrough late in 2004. But Sudanese Vice President Ali Osman Taha was threatening to walk out of the talks. There was nothing left to discuss, he insisted. The wily rebel leader John Garang - who had led the fight against the Sudanese government for nearly two decades - was being completely unreasonable, he said.

Sumbeiywo had seen this kind of brinkmanship before. One side or the other would pack their bags and send them to the hotel lobby - only to return to the table. But this time Mr. Taha seemed to mean it. His personal plane was en route and had been cleared to land at the airport near the Kenyan resort town of Naivasha. Sumbeiywo and his staff were desperate. They started using every "back channel and front channel" they could think of, Page recalls.

And Sumbeiywo played his strongest ace: Colin Powell.

He phoned Washington, asking the US secretary of State to help.

Mr. Powell was soon working the phones, calling Messrs Taha and Garang, as he often did, within an hour of each other. "We can't miss this opportunity," Powell recalls telling them, in a recent phone interview.

Powell had leverage because ever since Sept. 11, 2001, Sudan's government was desperate to please the US. Back in the 1990s it had hosted Osama bin Laden and other terrorists. It now feared its "terrorist haven" label and economic pariah status would continue. Or worse, that the US might invade.

That moment in the process was emblematic of how the US and other outside players acted as force-multipliers to Sumbeiywo's efforts. Although they sometimes pushed too hard, Sumbeiywo says, having Powell, Danforth, and President Bush backing him was crucial.

Of course, American officials saw an opportunity to help end Africa's longest war - and score a victory with key US voting constituencies: Christian conservatives who objected to the Khartoum's imposition of Islam and slavery on southern Christians; and African-Americans, who resented the Arab-dominated government's mistreatment of southern blacks.

Yet the Americans also knew how tough Sumbeiywo's task was: Danforth recalls Mr. Bush once telling him that, with all the religious and ethnic strife between the two sides, "If they can work it out, anybody can."

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The moment-by-moment midwifing of a peace process by a single mediator - like Sumbeiywo and Betty Bigombe in Uganda - represents a shift away from the old pattern of peacemaking in Africa, experts say. It used to be that high-profile heads of state would swoop in to a troubled country and try to knock heads to get a deal. That's what Nelson Mandela, then president of South Africa, did in Burundi in the 1990s. The trouble is that "you've got eight minutes to make peace" before the big man gets back on the plane, says Peter Kagwanja of the International Crisis Group in Pretoria, South Africa. By contrast, he says, "the Sumbeiywos have nothing else to do but negotiate."

But these peace seekers need lots of support.

And Sumbeiywo had it from global players like the US. But he was actually employed by a regional group of seven nations called the Intergovernmental Authority on Development (IGAD). Increasingly, observers say, it's groups like IGAD, the Economic Community of West African States (ECOWAS), and the African Union that are stepping up to solve Africa's conflicts. The African Union, for instance, is sponsoring peace talks to end the Darfur crisis. And it's the only outside organization with troops on the ground in Darfur.

"Having a strong African leader, with the confidence of regional governments, who's backed by high-level envoys from countries that matter" - like the US - is "the model for conflict resolution in Africa," says John Prendergast in the International Crisis Group's Washington office. "You've got to get the process right." And, he says, Sumbeiywo did.

* * *

But the outside players weren't always helpful. Sometimes Sumbeiywo had to draw the line.

The Americans, British, and Norwegians, plus church groups, aid agencies, and others who had observer teams at the talks would try to speed the negotiations by "promising things they couldn't deliver," says Page. One team, for example, pledged there would be a sharia-free capital of Sudan - a goal of the southern rebels.

The Americans were some of the biggest offenders. In the run-up to Bush's 2004 State of the Union speech, US officials were desperate for a foreign-policy victory to offset mounting criticism over Iraq. So they pushed hard to seal the deal. The pressure from all sides got so bad that the negotiators pleaded with Sumbeiywo to "protect us," Page recalls.

Sumbeiywo admonished the outside observers to "let the parties have their time." And he set the boundary: The swimming pool area of the lakeside resort hotel, and no further. This kept them far enough away from the talks that it limited their ability to interfere.

The rule reflected Sumbeiywo's philosophy that the parties themselves had to forge the deal. He and the observers could facilitate - but not force. Sumbeiywo's chlorine boundary line "really improved the process," says one Western diplomat who was there.

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The warring parties were finally willing to take the last steps toward peace, Sumbeiywo says, because they knew the costs of war - and the potential economic benefits of ending it. Civil wars cost African economies 2.2 percent in GDP growth per year, according to a study published last year by Oxford University. By that measure, Sudan's war sapped more than 46 percent from the economy's growth during its 21 years.

And now, in the wake of the peace pact, the country is booming. At a mid-April conference in Norway, donor nations pledged $4.5 billion in reconstruction aid. The rest of the $7.9 billion cost of rebuilding will come from Sudan's oil exports, which are also rising as new investment boosts production. The country has huge oil reserves, mostly in the south. Until recently, Sudan exported a relatively small 300,000 barrels a day. But the foreign minister predicted recently that the rate would reach 2 million daily by 2008.

* * *

On the sun-dappled afternoon of Jan. 9, 2005, at a packed soccer stadium in Nairobi, the parties were arriving to sign the final peace deal. But as the morning dragged on, tensions rose. There was a seating problem: Not all the visiting dignitaries had seats in the tented VIP section.

Sumbeiywo wasn't going to let protocol compromise the day. He marched to the podium, and began negotiating a new seating arrangement. He got Kenyan ministers and other lower-level officials to vacate seats in favor of visiting diplomats. He also organized a squad of porters to bring in extra chairs.

Finally, in a white tent in the middle of the grass field, the two sides put their signatures on the deal. Men danced and women ululated. Scores of happily seated diplomats, including Powell, applauded vigorously.

The event marked the end of one of the world's deadliest conflicts - and, for Sumbeiywo, of so many sleepless nights. "It was reached by the will of God," he says.

But Sumbeiywo knows the peace process is only beginning. "Half of an agreement is in the implementation," he says. Under this deal, the parties have six years to take steps to prevent war from reigniting - such as integrating their armies into one national defense force. At the end of the six years, southern Sudanese will vote on whether they want to secede from the north.

Throughout this year, the parties were moving forward on schedule. On July 9, SPLA leader Garang was sworn in as first vice president in Sudan's new government - making him the first southern Christian to hold a top post in the country's largely Arab Muslim government.

Just three weeks later, though, the implementation process was shaken deeply when Garang was killed in a night-time helicopter crash.

Many feared this would derail the peace pact. It hasn't so far. But observers say that Sumbeiywo's role as guardian of the deal now becomes even more important. He's one of the few people who knows exactly what Garang and the others meant when they compromised on certain issues.

"We hope IGAD and Sumbeiywo stay involved," says Gary McGurck, who works on Sudan for the international aid group CARE. "The best thing Sumbeiywo can say is, 'I'm available and I'm willing if you both want me.' "

For his part, Sumbeiywo is enjoying a slower pace. "It's been a lot of Christmases since I've seen my family," he says. So now, "I can make up for it."

But his voice turns to steel when he talks about Sudan's continued peace. "We must watch," he says. "We must watch very carefully."